java单例模式

public class SingletonTest {    public static void main(String[] args) {        System.out.println("Start");        Singleton obj1 = Singleton.getInstance();        Singleton obj2 = Singleton.getInstance();        if(obj1 == obj2){            System.out.println("obj1和obj2是同一个对象实例");        }else{            System.out.println("obj1和obj2并非同一对象实例");        }        System.out.println("end");    }}class Singleton {    private static Singleton singleton = new Singleton();    private Singleton(){        System.out.println("已产生实例对象");    }    public static Singleton getInstance(){        return singleton;    }}